US7498913B2 - Thermal trip device and circuit breaker using the same - Google Patents

Thermal trip device and circuit breaker using the same Download PDF

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Publication number
US7498913B2
US7498913B2 US10/592,003 US59200304A US7498913B2 US 7498913 B2 US7498913 B2 US 7498913B2 US 59200304 A US59200304 A US 59200304A US 7498913 B2 US7498913 B2 US 7498913B2
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Prior art keywords
bimetal
temperature
trip
trip device
black
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US10/592,003
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US20070195478A1 (en
Inventor
Kouji Kawamura
Hiroyuki Akita
Masatoshi Murai
Hirotoshi Yonezawa
Satoru Naito
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Assigned to MITSUBISHI ELECTRIC CORPORATION reassignment MITSUBISHI ELECTRIC CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AKITA, HIROYUKI, YONEZAWA, HIROTOSHI, NAITO, SATORU, KAWAMURA, KOUJI, MURAI, MASATOSHI
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10—Operating or release mechanisms
    • H01H71/12—Automatic release mechanisms with or without manual release
    • H01H71/14—Electrothermal mechanisms
    • H01H71/16—Electrothermal mechanisms with bimetal element
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
    • H01H11/0062—Testing or measuring non-electrical properties of switches, e.g. contact velocity
    • H01H2011/0068—Testing or measuring non-electrical properties of switches, e.g. contact velocity measuring the temperature of the switch or parts thereof

Definitions

  • the present invention relates to a thermal trip device and a circuit breaker using the same.
  • a thermal trip device is, for example, a device that detects overcurrent in a circuit breaker to trip a main circuit.
  • Trip characteristic when overcurrent flows has its range stipulated by standard such as JIS (Japanese Industrial Standard) and products need to comply with it.
  • JIS Japanese Industrial Standard
  • a thermal trip device however, variation in trip characteristic is inevitable due to manufacturing variation of constitutional components and material variation. Consequently, a structure for adjusting the trip characteristic is usually incorporated to adjust and inspect the characteristic.
  • the trip characteristic In order to adjust and inspect the trip characteristic, its characteristic value needs to be accurately measured.
  • the trip characteristic In the thermal trip device, the trip characteristic is often measured by measuring a time (trip time) from energization initiation to trip completion and an amount of displacement of a bimetal by supplying a predetermined current. Meanwhile, curvature factor of a bimetal is known and therefore the amount of displacement of the bimetal can be determined by measuring a bimetal temperature. Therefore, the trip characteristic can be figured out by measuring the bimetal temperature.
  • a method of no-contact measurement is preferable in order not to affect on an amount of curvature of the bimetal by measurement.
  • load is applied to a bimetal from outside via a probe and therefore deflection is generated in the bimetal to cause change in trip characteristic.
  • an emission thermometer incorporating an infrared absorption element is commonly used.
  • the present invention is implemented to solve such problems, and an object of the present invention is to provide a thermal trip device and a circuit breaker using the same, capable of highly accurately measuring a bimetal temperature using a no-contact thermometer.
  • a thermal trip device in which a bimetal is heated by overcurrent and performs trip operation of a circuit by curvature of the heated bimetal, wherein at least one part of the surface of the bimetal is made to be black or matte black.
  • thermometer temperature of the bimetal can be highly accurately measured using a no-contact thermometer.
  • the surface of a temperature measurement part of the bimetal is made to be black or matte black.
  • the temperature measurement part of the bimetal is provided with a bending part bent substantially perpendicular to longitudinal direction, and the surface of the bending part is made to be black or matte black.
  • a temperature measurement part of the bimetal is provided with a bending part bent substantially perpendicular to longitudinal direction.
  • FIG. 1 is a perspective view showing a bimetal part of a thermal trip device according to a first embodiment of the present invention
  • FIG. 2 is a perspective view showing a bimetal part of a thermal trip device according to a second embodiment
  • FIG. 3 is a perspective view showing a bimetal part of a thermal trip device according to a third embodiment
  • FIG. 4 is a perspective view showing a bimetal part of a thermal trip device according to a fourth embodiment
  • FIG. 5 is a plan view showing a material processing step of the bimetal according to the second embodiment
  • FIG. 6 is a plan view showing a material processing step of the bimetal according to the third embodiment.
  • FIG. 7 is a view showing a state where temperature of the bimetal of the third embodiment is measured using a no-contact thermometer
  • FIG. 8 is a view showing a state where temperature of the bimetal of the third embodiment is measured using a no-contact thermometer.
  • FIG. 9 is a partially cutaway front view showing a structure of a circuit breaker having a thermal trip device.
  • a circuit breaker is a safety device that interrupts a circuit to prevent accident when overcurrent which is not lower than rating flows.
  • a mechanism that detects overcurrent in the circuit breaker is referred to as a trip mechanism; and as one of detecting means thereof, there is a thermal type using a bimetal. This is one, which uses a property that the bimetal curves depending on temperature change.
  • FIG. 9 is a thermal trip mechanism and, more specifically, is a partially cutaway front view showing a structure of a circuit breaker having a thermal trip device.
  • the range of a time from when the overcurrent flows till the overcurrent trips is stipulated by standard such as JIS and trip time of products must comply with its range.
  • an operational point of the trip mechanism that is, a position where the bimetal 2 presses the trip bar 3 changes due to accumulation in manufacturing variation such as error in processing and assembling and variation in material characteristics of each component constituting the trip mechanism; and variation in a time (trip time) from energization initiation to trip completion is generated. Consequently, in order to absorb such manufacturing variation, an adjustment mechanism 6 is provided at a top end of the bimetal 2 and the trip bar 3 to perform adjustment and inspection work in the assembling step.
  • trip characteristic for each workpiece needs to be accurately measured.
  • the trip characteristic is often measured by measuring the trip time by supplying a predetermined current value and by measuring an amount of displacement of the bimetal during that time.
  • the trip time and the amount of displacement of the bimetal are largely affected by workpiece temperature at energization initiation and measurement environment temperature; and therefore, the measurement must be performed in a state controlled at a constant temperature or the measurement value must be corrected on the basis of the workpiece temperature and ambient temperature.
  • the bimetal is determined by an amount of curvature (an amount of displacement) on the basis of its temperature and a curvature factor; however, the curvature factor is known and therefore the amount of displacement can be determined by measuring the bimetal temperature. Therefore, the trip characteristic can be measured by measuring the bimetal temperature.
  • a no-contact emission thermometer is commonly used. This is because that when a contact thermometer is used, deflection of the bimetal is generated due to contact load of a probe to change trip characteristic, so that accurate trip characteristic cannot be measured.
  • the no-contact thermometer measures an object's temperature by detecting an amount of emission energy of infrared rays emitted from the object.
  • An amount of infrared radiation differs depending on a material and a surface state; and an amount of emitted infrared energy (emissivity) is different even at the same temperature.
  • the no-contact thermometer calculates temperature on the basis of an ideal black body (theoretical body of emissivity 100%) and an object other than that must be corrected in accordance with each emissivity.
  • the emissivity can be usually obtained on a trial basis. Since it is difficult to determine emissivity of a measured object in a short time, the emissivity cannot be determined for each workpiece in the mass production step. Therefore, in the case where the emissivity of the bimetal varies, its variation becomes variation of temperature measurement. Further, the bimetallic surface is usually a metallic luster surface and therefore infrared rays emitted from other heat source in the vicinity of the bimetal such as a heater or the like are easy to be reflected on the bimetallic surface. If the reflected light enters into an emission thermometer, it causes measurement error.
  • temperature measurement is possible by correcting depending on the emissivity even in the case where the emissivity is low; however, an absolute amount of the infrared rays reduces and therefore noise components in measuring increase to cause accuracy degradation in the temperature measurement. Consequently, it is preferable that the emissivity is high and constant for highly accurate temperature measurement.
  • the surface serving as a temperature measurement part of the bimetal 2 is made to be black, preferably matte black 7 (refer to FIG. 1 ), thereby increasing the emissivity and being constant.
  • reflection from other heat source can be suppressed by a matte coating and measurement error can be reduced.
  • FIG. 1 is a perspective view showing a bimetal part of a thermal trip device according to a first embodiment of the present invention.
  • black for example, there is a method such as coating and etching.
  • matte black coating may be used.
  • etching solution for example, sodium hydroxide solution and phosphate solution are used when the bimetal 2 is an iron group material; and, for example, acid aqueous solution containing selenium is used when it is a copper group material.
  • FIG. 2 is a perspective view showing a bimetal part of a thermal trip device according to a second embodiment.
  • the bimetal 2 for use in a circuit breaker is manufactured by press working from an elongate bimetallic material 9 (refer to FIG. 5 ). Therefore, only a part to be the temperature measurement part in a step of the material 9 is made to be black, preferably matte black 7 ; and by performing press working on it, a bimetallic strip in which only a necessary part is blackened can be obtained.
  • FIG. 5 is a plan view showing a material processing step of the bimetal according to the second embodiment. Blackening process performed in a state of the bimetallic strip is more simplified and reduced in processing cost than blackening process performed in a state of the material in block. Furthermore, minimizing the processing part as in the second embodiment can further reduce processing cost.
  • FIG. 6 An example where two black parts are provided on a bimetallic material 9 is shown in FIG. 6 .
  • a bimetal shape that gradually narrows toward a top end; and in this case, orientation of bimetallic strips is alternatively combined and press worked, whereby yield of the material 9 can be increased.
  • the bimetallic material 9 drawn out from a rolled material is provided with two black parts and press worked as shown in the drawing.
  • a perspective view of a principal part of a thermal trip device using the bimetal formed in a third embodiment is shown in FIG. 3 .
  • FIG. 7 is a view showing a state where the bimetal 2 of the third embodiment is measured using a no-contact thermometer 10 .
  • an electric leakage detection section is incorporated in an electric leakage circuit breaker adjacent to the bimetal and there are many cases where the above-mentioned space cannot be secured. Furthermore, in also a circuit breaker, points that can measure a bimetal temperature are limited due to downsizing of the product and there is a case where it is impossible to measure ideal temperature measurement points on the bimetal. A fourth embodiment is possible to perform temperature measurement at desired points even in such a case.
  • FIG. 4 A perspective view of a bimetal part of a thermal trip device according to a fourth embodiment is shown in FIG. 4 .
  • a bending part 11 is provided at a point serving as a temperature measurement part 8 of the bimetal.
  • a bending part 11 is provided substantially perpendicular to longitudinal direction of the bimetal 2 at the temperature measurement part 8 of the bimetal so as to measure temperature from the longitudinal direction of the bimetal.
  • a measurable space is often provided in the longitudinal direction of the bimetal 2 because it is necessary to have a space for bending the bimetal 2 and to adjust trip characteristic.
  • it is very difficult to measure temperature because in a conventional bimetal, only a measurable space as much as thickness is provided from this direction.
  • bending process is applied to a part which is the temperature measurement part 8 of the bimetal 2 to provide a bending part 11 so as to secure an area necessary for temperature measurement, whereby it is possible to measure temperature from upper side by a no-contact thermometer 10 parallel to a longitudinal direction of the bimetal 2 , as shown in FIG. 8 . It is possible to measure temperature at any location of the bimetal by changing a position to which the bending process is applied.
  • a part where temperature measurement is performed at the surface of the bending part is made to be black, preferably matte black, after the bending process or before the bending process; it is possible to further highly accurately measure the bimetal temperature.
  • a thermal trip device As described above, a thermal trip device according to the present invention become possible to highly accurately measure bimetal temperature using a no-contact thermometer and therefore an amount of displacement of the bimetal can be precisely determined; this device is suitably applied to a circuit breaker; and characteristic of the circuit breaker can be easily stabled.

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  • Thermally Actuated Switches (AREA)
  • Breakers (AREA)
US10/592,003 2004-04-21 2004-04-21 Thermal trip device and circuit breaker using the same Expired - Lifetime US7498913B2 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2004/005705 WO2005104159A1 (ja) 2004-04-21 2004-04-21 熱動式引き外し装置及びそれを用いた回路遮断器

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US20070195478A1 US20070195478A1 (en) 2007-08-23
US7498913B2 true US7498913B2 (en) 2009-03-03

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US (1) US7498913B2 (de)
EP (1) EP1739703B1 (de)
JP (1) JP4369475B2 (de)
CN (1) CN100521031C (de)
HK (1) HK1099843A1 (de)
TW (1) TWI234795B (de)
WO (1) WO2005104159A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120242429A1 (en) * 2010-03-03 2012-09-27 Walter Michael Pitio Circuit Breaker

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009176655A (ja) * 2008-01-28 2009-08-06 Kawamura Electric Inc 回路遮断器の過電流引き外し装置

Citations (18)

* Cited by examiner, † Cited by third party
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US3261947A (en) * 1963-04-03 1966-07-19 Philips Corp Bimetallic switch cutout
GB1419528A (en) * 1971-12-16 1975-12-31 Bosch Gmbh Robert Device for monitoring the heating of heater plugs of an internal combustion engine
US4106482A (en) * 1976-04-27 1978-08-15 Savage Fred L Autonomic solar panel
US5317471A (en) * 1991-11-13 1994-05-31 Gerin Merlin Process and device for setting a thermal trip device with bimetal strip
JPH11219645A (ja) * 1998-01-30 1999-08-10 Matsushita Electric Works Ltd ハイブリッドリレー
US6135633A (en) * 1997-09-30 2000-10-24 Siemens Energy & Automation, Inc. Method for thermally calibrating circuit breaker trip mechanism and associated trip mechanism
US6215379B1 (en) * 1999-12-23 2001-04-10 General Electric Company Shunt for indirectly heated bimetallic strip
US6246241B1 (en) * 1998-02-06 2001-06-12 Siemens Energy & Automation, Inc. Testing of bimetallic actuators with radio frequency induction heating
JP2002245919A (ja) 2001-02-14 2002-08-30 Matsushita Electric Works Ltd 回路遮断器のバイメタル固定装置
US6466424B1 (en) * 1999-12-29 2002-10-15 General Electric Company Circuit protective device with temperature sensing
JP2002324473A (ja) 2001-04-24 2002-11-08 Matsushita Electric Works Ltd 回路遮断器とその調整方法及び調整装置
US20030043522A1 (en) * 2001-08-27 2003-03-06 Schmalz Steven Christopher Circuit breaker, trip assembly, bimetal compensation circuit and method including compensation for bimetal temperature coefficient
US6580351B2 (en) * 2000-10-13 2003-06-17 George D. Davis Laser adjusted set-point of bimetallic thermal disc
US6803850B2 (en) * 2002-10-10 2004-10-12 Square D Company Thermal trip assembly and method for producing same
US6816055B2 (en) * 2001-01-31 2004-11-09 Siemens Aktiengesellschaft Adjusting device for a thermal trip element
US7135953B2 (en) * 2001-07-02 2006-11-14 Siemens Aktiengesellschaft Adjusting device for a thermal trip
US20070165349A1 (en) * 2006-01-17 2007-07-19 Eaton Corporation Circuit breaker and method for sensing current indirectly from bimetal voltage and determining bimetal temperature and corrected temperature dependent bimetal resistance
US7279218B2 (en) * 2004-01-23 2007-10-09 Kobe Steel, Ltd. Coated body having excellent thermal radiation property used for members of electronic device

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BE442165A (de) * 1940-07-27
US4630019A (en) * 1984-09-28 1986-12-16 Westinghouse Electric Corp. Molded case circuit breaker with calibration adjusting means for a bimetal
JPH01286213A (ja) * 1988-05-12 1989-11-17 Toshiba Corp Ｓｆ↓６ガス絶縁電力機器の赤外線温度検出システム

Patent Citations (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3261947A (en) * 1963-04-03 1966-07-19 Philips Corp Bimetallic switch cutout
GB1419528A (en) * 1971-12-16 1975-12-31 Bosch Gmbh Robert Device for monitoring the heating of heater plugs of an internal combustion engine
US4106482A (en) * 1976-04-27 1978-08-15 Savage Fred L Autonomic solar panel
US5317471A (en) * 1991-11-13 1994-05-31 Gerin Merlin Process and device for setting a thermal trip device with bimetal strip
US6135633A (en) * 1997-09-30 2000-10-24 Siemens Energy & Automation, Inc. Method for thermally calibrating circuit breaker trip mechanism and associated trip mechanism
JPH11219645A (ja) * 1998-01-30 1999-08-10 Matsushita Electric Works Ltd ハイブリッドリレー
US6246241B1 (en) * 1998-02-06 2001-06-12 Siemens Energy & Automation, Inc. Testing of bimetallic actuators with radio frequency induction heating
US6215379B1 (en) * 1999-12-23 2001-04-10 General Electric Company Shunt for indirectly heated bimetallic strip
US6466424B1 (en) * 1999-12-29 2002-10-15 General Electric Company Circuit protective device with temperature sensing
US6580351B2 (en) * 2000-10-13 2003-06-17 George D. Davis Laser adjusted set-point of bimetallic thermal disc
US6816055B2 (en) * 2001-01-31 2004-11-09 Siemens Aktiengesellschaft Adjusting device for a thermal trip element
JP2002245919A (ja) 2001-02-14 2002-08-30 Matsushita Electric Works Ltd 回路遮断器のバイメタル固定装置
JP2002324473A (ja) 2001-04-24 2002-11-08 Matsushita Electric Works Ltd 回路遮断器とその調整方法及び調整装置
US7135953B2 (en) * 2001-07-02 2006-11-14 Siemens Aktiengesellschaft Adjusting device for a thermal trip
US20030043522A1 (en) * 2001-08-27 2003-03-06 Schmalz Steven Christopher Circuit breaker, trip assembly, bimetal compensation circuit and method including compensation for bimetal temperature coefficient
US6803850B2 (en) * 2002-10-10 2004-10-12 Square D Company Thermal trip assembly and method for producing same
US7279218B2 (en) * 2004-01-23 2007-10-09 Kobe Steel, Ltd. Coated body having excellent thermal radiation property used for members of electronic device
US20070165349A1 (en) * 2006-01-17 2007-07-19 Eaton Corporation Circuit breaker and method for sensing current indirectly from bimetal voltage and determining bimetal temperature and corrected temperature dependent bimetal resistance

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120242429A1 (en) * 2010-03-03 2012-09-27 Walter Michael Pitio Circuit Breaker
US8958192B2 (en) * 2010-03-03 2015-02-17 Cedarwood Technologies, Inc. Circuit breaker

Also Published As

Publication number Publication date
CN1926654A (zh) 2007-03-07
EP1739703A1 (de) 2007-01-03
TWI234795B (en) 2005-06-21
CN100521031C (zh) 2009-07-29
WO2005104159A1 (ja) 2005-11-03
JPWO2005104159A1 (ja) 2008-03-13
EP1739703A4 (de) 2009-10-21
EP1739703B1 (de) 2012-07-11
JP4369475B2 (ja) 2009-11-18
HK1099843A1 (en) 2007-08-24
TW200535888A (en) 2005-11-01
US20070195478A1 (en) 2007-08-23

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